The neutral position of the control sticks can be incorrectly set if you move them during the following actions:
Turning the console on
Quitting software and returning to the Wii U Menu
What to do:
Power on the Wii U Console and Wii U GamePad.
Allow the control sticks to return to a neutral untouched position
Simultaneously hold down the A Button, B Button, + Button, and – Button for at least 3 seconds.